Method for the treatment of shredded cheese with a polyene antifungal compound

ABSTRACT

A method for the treatment of shredded cheese with an aqueous composition whereby the aqueous composing comprises a polyene antifungal compound e.g. notamycine and a thickening agent, e.g. xanthan. Use of a thickening agent to prevent nozzle clogging during the treatment of food, feed and agricultural products with an aqueous composition.

FIELD OF THE INVENTION

The present invention relates to a method for the treatment of shreddedcheese with a polyene antifungal compound.

BACKGROUND OF THE INVENTION

The prevention of mould growth is an important topic to the food, feedand. agricultural industry, especially in the food industry. Fungalspoilage can lead to serious economic losses. Some foods can beconsidered as a good substrate for fungal growth. Cheese is an exampleof such a product. Apart from the negative appearance of fungal growthon cheese, fungal spoilage is also a health risk. Some mould speciesproduce mycotoxins, which may penetrate into the product (J. C. Frisvad& U. Thane; “Mycotoxin production by food-borne fungi” in Introductionto food-borne fungi, 4^(th) edn. (ed. R. A. Samson et al.), 1995,251-260. Therefore, superficial removal of moulds gives no guarantee ofsafety to the consumer.

For more than 30 years, natamycin has been used to prevent growth ofmoulds and yeasts on cheeses and sausages. Natamycin is on the marketunder the brand name of Delvocid®, a powder composition containing 50%(wlw) of natamycin.

Food products can be treated with natamycin in different ways. Natamycincan for example be added to the polymer dispersion that is applied tothe cheese rind as a coating (C. B. G. Daamen & G. van den Berg“Prevention of mould growth on cheese by means of natamycin”Voedingsmiddelentechnologie, 1985, 18 (2), 26-29)

Alternatively, food products such as cheeses and sausages can be treatedby dipping or spraying with a suspension of natamycin in water (C. B. G.Daamen & G. van den Berg “Prevention of mould growth on cheese by meansof natamycin” Voedingsmiddelentechnologie, 1985, 18 (2), 26-29; H. A.Morris & H. B. Castberg “Control of surface growth on blue cheese usingpimaricin” Cultured Dairy Products Journal, 1980, 15 (2), 21-23; P.Baldini, F. Palmia, R. G. Raczynski, M. Campanini, “Use of pimaricin forpreventing mould growth on Italian cured meat products”, IndustriaConserve, 1979, 54 (4), 305-307; R. A. Holley, “Prevention of surfacemould growth on Italian dry sausage by natamycin and potassium sorbate”,Appl. Environ. Microbiol., 1981, 41 (2).

Spraying of a suspension of natamycin can be applied for the treatmentof shredded cheese, a cheese product which is very sensitive to fungalspoilage. The production of shredded cheese is as follows: cheese, e.g.Mozarella, pizza cheese, or Cheddar is shredded and conveyed to arevolving tumbler. An anti-caking agent, for example cellulose(microcrystalline or powdered), starch or modified starch is meteredonto the cheese in the first part of the tumbler. Cellulose forms a filmaround the cheese particles which prevents caking of the shreddedcheese. At the end of the tumbler a suspension of natamycin (e.g.Delvocid®) is sprayed onto the shredded cheese. The spray nozzlesdeliver a fine spray or mist of the fungicide onto the cheese. Finally,the cheese empties onto a conveyor to be transported to the fillingequipment.

The natamycin suspension is prepared by mixing Delvocid® and water,mostly at the ratio from 2 to 10 grams of Delvocid® to 1 litre of water.The suspension is stored in a liquid container. To prevent sedimentationof the suspension a small amount of the suspension, which is pumpedunder pressure to spray nozzles, is recirculated to the liquid containervia a jet agitator. Alternatively, a stirring device can be used toprevent sedimentation. Mostly approximately 6 to 8 litres of Delvocid®suspension is sprayed onto 1000 kg of cheese. Mostly this treatment iseffective to prevent fungal spoilage.

The spraying or showering of aqueous suspensions on cheeses usingnozzles is an effective way of coating the cheeses with the antifungalcompounds. In general a less fine spray is used for spraying of completecheeses. This spray or shower will be focused or directed onto thecheese. However for spraying of shredded cheese, the suspension shouldbe added as a fine spray or mist. This spraying method often gives riseto problems such as the clogging of the spraying nozzles.

DESCRIPTION OF THE INVENTION

It now has been found that protection against the development of mouldsand yeasts shredded cheese is obtained in a method for the treatmentshredded cheese with a composition comprising a polyene antifungalcompound, whereby the composition comprises a polyene antifungal agent,a thickening agent and water. Surprisingly it has been found that thethickening agent prevents the clogging of the nozzles. Moreover theaqueous composition can be pumped under pressure to and through thenozzles without problems which would have been expected due to theexpected increase of viscosity of the aqueous composition of theinvention compared to an aqueous composition without thickening agent.Especially xanthan gives very good results.

Therefore the present invention relates to a method for the treatment ofshredded cheese with an aqueous composition whereby the aqueouscomposition comprises a polyene antifungal compound and a thickeningagent. The present invention also relates to products produced with thepresent method. Shredded cheese coated with a polyene antifungalcompound and thickening agent forms part of this invention. A thickeningagent is used to prevent the nozzle clogging during the treatment offood, feed and agricultural products with an aqueous composition.

The polyene antifungal compounds used in the composition of theinvention are preferably one or more of natamycin, nystatin,lucensomycin or amphotericin B. The preferred polyene compound isnatamycin. In the preparation of compositions of the invention, one ormore polyene antifungal compounds may be used or pre-preparedcompositions containing such antifungal components may be used. Anexample of such a preparation is commercially available powdercomposition sold under the trade mark Delvocid® which contains 50% (w/w)natamycin.

The concentration of polyene fungicide in the aqueous composition willgenerally be from 0.1 to 20 g/l, more preferably from 0.5 to 8 g/l andmost preferably from 1 to 5 g/l.

In compositions of the invention the preferred thickening agents includeall thickening agents known in the art for use in food products,preferably the thickening agents are gum, more preferably xantan gumand/or gellan gum.

The one or more thickening agents in the aqueous composition arepreferably present in an amount of 0.5 to 50 g/l, more preferably from0.5 to 20 g/l and most preferably from 1 to 5 g/l.

In some embodiments it has been found that no buffer is needed for thesuspension. In general the pH of the suspension will be between 3-10,preferably the pH will be between 6-9, more preferably between 6.2-8.5for the optimal natamycin addition.

Preferably also an anticaking agent is added to the shredded cheese. Theanticaking agent preferably is a dry powder composition, which is addedseparately from the aqueous composition. In general 0.2 to 3% w/w ofanticaking agent (on shredded cheese) preferably between 1.5 and 2.5%w/w.

The steps of adding the dry powder composition and the aqueouscomposition may be performed in any order. Preferably, the dry powdercomposition is added before the aqueous composition is added.

The amount of the aqueous composition added to the shredded cheese maybe between 0.01% and 5% (v/w), preferably said amount is at least 0.5%or preferably lower than 2% (v/w).

In a preferred embodiment, the aqueous composition used in the methodaccording to the present invention is an aqueous solution or an aqueousdispersion such as an emulsion or suspension.

The optimal final concentration of natamycin added according to themethod of the present invention, may vary with the type of cheese usedas shredded cheese or the kind of shredded used. To prevent fungalgrowth on shredded cheese, the optimal final concentration may bebetween 2 and 40 ppm natamycin, preferably the concentration is at least3 ppm natamycin, more preferably at least 4 ppm natamycin. Theconcentration is preferably lower than 20 ppm, more preferably lowerthan 10 ppm.

Any anti-caking agent may be used. Examples of suitable anti-cakingagents are microcrystalline or powdered cellulose, starch, modifiedstarch, sodium-, magnesium-, potassium-, and zinc silicate,silicium-dioxide, kaolin, talc, potassium and magnesium carbonate,phosphates (di, tri and polyphosphates including sodium, potassium andcalcium salts). Also commercial products containing cellulose, such asKeycel or Floam® may be used as anti-caking agent. Further, anycombination of anti-caking agents may be used.

The aqueous composition comprising an antifungal compound, e.g.natamycin, may be prepared by mixing a dry formulation, e.g. Delvocid®,in water using well known methods. Preferably a natamycin suspension forspraying is prepared by using a stock suspension of natamycin asdescribed in EP 0 678 241. This stock suspension is a chemically,physically and microbially stable concentrated suspension of natamycin,which provides a convenient stock for the easy and reproducable dosageof a fungicide to food, feed and agricultural products. Apart fromnatamycin, the suspension comprises a thickening agent, for examplexanthan. The concentration of natamycin in the stock suspension may beas high as 40% (w/w), however also stock suspensions with lowerconcentrations of natamycin can be used. An example of such a stocksuspension is the commercial product Delvocid®-Sol. This productcomprises at least 50% (w/w) of natamycin; for example 50 to 54% (w/w)of natamycin, 2% (w/w) of xanthan and 44 to 48% (w/w) of lactose. In thecase of shredded cheese the stock suspension is diluted with water tothe final concentration required for the treatment. This dilution stepcan be best executed just before adding the natamycin suspension to theshredded cheese.

In cases where the polyene antifungal compound is natamycin, complexesof natamycin (e.g. with proteins) and salts of natamycin (e.g. thecalcium salt) may also be used in the method according to the presentinvention. Further, the dry and aqueous compositions may also containcomponents, which are already present in a natamycin preparation. Forexample, when Delvocid-Instant® or Natamax® is used, lactose will alsobe present in the final composition.

The following Examples are for illustrative purposes only and are not tobe construed as being limiting to the invention.

EXAMPLES

Cheddar cheese was shredded using well known methods and conveyed to arevolving tumbler. Microcrystalline cellulose was metered onto theshredded cheese in the first part of the tumbler and thoroughly mixedinto the shredded cheese. At the other side of the tumbler, extendingabout 30-60 cm into the tumbler, spray nozzles are situated (S. S.Fogger Tip Assembly #22624-2 80: 80° angle, 2 gal. (8 liters) per hourat 80 PSI (5.3 bar, purchased from Spraying Systems Co. PO Box 95584Chicago Ill. 60694). The nozzles are able to deliver a fine spray ofmist of one of the following natamycin formulations. Two experimentswere carried out using either formulation A (reference) or formulation B(present invention).

-   -   A) A suspension of Delvocid®, available by DSM Food Specialties        USA, by mixing 10 grams of Delvocid® with 4 liters of tapwater.    -   B) A suspension of Delvocid® and xanthan by mixing 10 grams of        Delvocid® with 4 liters of tapwater together with 3 grams        Keltrol® RD, available by NutraSweet Kelco Company.

Both suspensions were sprayed on shredded cheese with a flow of 10liters per hour. The spray characteristics were followed in time duringa 2 shift operation, 16 hours per day.

During the tests it was shown that the nozzles could be used withsuspension A for a 1-6 hour operation. After this period the nozzleswere completely blocked by clogging. The nozzles needed to be cleanedcompletely before further operation was possible. Using suspension Bresulted in a operation of 16 hours without any problems such asclogging.

1. A method for the treatment of a shredded cheese comprising the step of contacting the shredded cheese with an aqueous composition, wherein the aqueous composition comprises a polyene antifungal compound and a thickening agent.
 2. The method of claim 1, wherein the polyene antifungal compound comprises natamycin.
 3. The method of claim 1, further comprising adding a dry powder composition comprising an anticaking agent to the shredded cheese.
 4. The method of claim 3, wherein the dry powder composition is added before the aqueous composition.
 5. The method of claim 3 wherein the anticaking agent comprises cellulose or starch or modified starch.
 6. The method of claim 1, wherein the thickening agent comprises a xanthan.
 7. A processed cheese, wherein the cheese comprises a coating comprising a polyene antifungal compound and a thickening agent.
 8. The processed cheese of claim 7, wherein the thickening agent comprises a xanthan.
 9. A method for preventing nozzle clogging during the treatment of a food, a feed or agricultural products with an aqueous composition, comprising the step of contacting the food, feed or agricultural product with an aqueous composition comprising a polvene antifungal compound and a thickening agent.
 10. The method of claim 9, wherein the food, feed or agricultural product comprises a cheese cheese.
 11. The processed cheese of claim 7, wherein the cheese comprises a shredded cheese.
 12. The method of claim 10, wherein the cheese comprises a shredded cheese.
 13. The method of claim 5, wherein the cellulose comprises a microcrystalline cellulose.
 14. A method for the treatment of a food, a feed or an agricultural product comprising the step of contacting the food, feed or agricultural product with an aqueous composition, wherein the aqueous composition comprises a polyene antifungal compound and a thickening agent.
 15. A processed food, feed or agricultural product made by a method comprising the step of contacting the food, feed or agricultural product with an aqueous composition, wherein the aqueous composition comprises a polyene antifungal compound and a thickening agent.
 16. The processed food, feed or agricultural product of claim 14, wherein the food, feed or agricultural product comprises a cheese.
 17. The processed food, feed or agricultural product of claim 15, wherein the cheese comprises a shredded cheese.
 18. A processed food, feed or agricultural product, wherein the food, feed or agricultural product comprises a coating comprising a polyene antifungal compound and a thickening agent.
 19. The processed food, feed or agricultural product of claim 18, wherein the food, feed or agricultural product comprises a cheese.
 20. The processed food, feed or agricultural product of claim 19, wherein the cheese comprises a shredded cheese.
 21. The processed food, feed or agricultural product of claim 18, wherein the thickening agent comprises a xanthan.
 22. The processed food, feed or agricultural product of claim 18, wherein the coating further comprises an anticaking agent.
 23. The processed food, feed or agricultural product of claim 22, wherein the anticaking agent comprises a cellulose, a microcrystalline cellulose, a starch or a modified starch. 